The present invention relates to a device in a machine-control system and/or process-supervision system operating with the CAN-protocol according to standard ISO 11898. CAN-systems of this type comprise modules which are intercommunicable via a digital serial communication and in which a control and/or supervisory function can be realized from a first module or from a unit, which is communicable with the CAN-system, belonging to one or more second module(s). The present invention is a single-day application made together with Swedish patent application xe2x80x9cDevice in a control and/or supervision systemxe2x80x9d submitted by the same applicant and the same inventor.
The present invention relates to a device in a machine-control system or process-control system. The said system has in the present case been referred to as a CAN-system, since the systems in question are required to use the signal protocol according to CAN (Controller Area Network, corresponding to standard ISO 11898). The invention in this case relates to those types of CAN-system comprising modules which are connectable via a digital serial communication and in which a function in a first module is intended to be able to be observed, stimulated or registered at a location for the placement of the first module. Reference is also made to Swedish patent application xe2x80x9cDevice in a system operating with CAN-protocolxe2x80x9d, which was submitted on the same day by the same applicant and inventor.
It is previously known to be able to control machinery and equipment at control desks which are connected via fixed connections or wireless connections. These proposals make use of the general control and supervision principles. With reference to control desk arrangements proposed with CAN-protocol, the arrangements in question are primarily those with wire connections. Reference is also made to U.S. Pat. No. 5,392,454.
With machine-control and process-control systems of this category, it is previously known that it is necessary to supervise the aggregates served by the 10 modules such that in fault-searching, system design, etc., it is possible to establish whether the equipment controlled by a particular module is behaving as expected. It can be stated in this context that it may be necessary to monitor the functions at valves, thermometers, etc., so that in certain functional states it can be seen or registered whether the components in question are actually performing their expected function. It is also known to utilise machine-control systems and process-control systems in which the equipment parts are connected via relatively long digital serial communications. The connection can also be established at locations and sites where accessibility is limited.
In the radio-controlling of machines operating with CAN-protocol, problems arise from the fact that the protocol calls for arbitration and confirmation functions which are extremely time-critical. In order to ensure that the modules do not misinterpret a particular message in question, in certain cases the receipt of a one over the connection must result, for example, in a zero being immediately presented to prevent disturbances occurring within the system. This calls for sending and receiving to be effected simultaneously by one and the same module, which, in turn, calls for a full duplex connection and time synchronisation between the sending and receiving channel in each module and predetermined maximum wave propagation time within the system. This is difficult to achieve in a radio system when such a system is often chosen to enable the distance between the modules within a system which are connected by radio link to be easily varied. Radiocommunication is therefore less suitable for systems using the CAN-protocol. The object of the present invention is to solve these problems.
In certain contexts, it is vital to be able to make use of repetition functions linked to machines or machinery stocks operating with CAN-protocol. At places which are difficult to survey or difficult to access, there is a need to build up an existing CAN-system and introduce a repetition function over difficult stretches or to create on a temporary or longer term basis two separately working CAN-systems instead of one. In this context, there is a need to be able to facilitate system developments and system applications. The object of the invention is to solve these problems also.
There is also a need to achieve effective coordination of machine-controls in machinery stocks, e.g. in weaving sheds in which weaving machines have hitherto been controlled individually and provided with their own man-machine interface such as control desks. There is a wish to be able to introduce CAN-protocol into the control of machines of this category, this having been hindered by the above-specified problems. The object of the present invention is to solve these problems also and it is proposed, in respect of this category of machinery-stock control, that the controls be effected via radiocommunication from and to a common man-machine interface, such as a control unit or control desk. The control equipment is thereby simplified and a coordinated, effective control is able to be established in terms of service and production via or in the machinery stock.
Radiocommunication is often utilised between an operator""s control unit and the control system of the machine which he controls. Examples of such systems are radio-controlled airplanes, radio-controlled contracting machinery, radio-controlled hoisting cranes, etc. of various types. One problem is here to set up a radio channel which is exclusively between control unit and machine, such that the connection is not disturbed by other operator/machine connections. The object of the present invention is to solve this problem also.
The invention also allows reduced susceptibility to theft and offers high security within the system per se.
There is a great need to be able to carry out fault searches and tests on modules which are situated at a distance apart and in which a functional effect upon a first module is wanted to be able to be followed at a second module, and vice versa. For instance, there is a desire in certain situations to initiate controls at a master in the CAN-system in order to obtain manifestations at one or more slave modules. There is here a need to see whether the function is being correctly performed by the components or aggregates controlled by the module in question.
There is also a need to be able to stimulate a component or aggregate at a module and to discover what repercussions this has.
There is also a need to be able to carry out registration operations in a fault-searching and testing context for a certain period, as well as to acquire direct visual and signal information at the site for the module subjected to testing or fault-searching.
The above must be practicable even if the modules are far apart and hidden from each other. Preferably, the above will be able to be effected via an already existing switching function, i.e. connections and disconnections do not need to be made in each separate case/in respect of each module.
The invention aims to solve the whole or parts of the above problems.
What primarily can be considered to be characteristic of a device according to the invention is that it comprises two or more communication parts which form part of the CAN-system, respectively between the CAN-system and the unit mentioned in the introduction, and which are communicable via one or more wireless connections, that when a transmission is made from a first communication part to a second communication part, the parts operate with a signal protocol which takes no account of arbitration and/or confirmation function(s) found in the CAN-system. A particular receiving communication part executes or assists in the conversion of the said signal protocol to the signal protocol of the CAN-system.
In one embodiment, the communication parts can be coupled to the CAN-system, which in the non-connected or non-activated state of the communication parts forms a unitary system and which in the connected or activated state of the communication parts forms two CAN-systems which operate separately relative to each other.
A particular pair of communication parts can in this case operate with a protocol which is distinct from the CAN-protocol and is better suited for radiocommunication, e.g. Aloha, Ethernet, the xe2x80x9cGPSPxe2x80x9d WaveRaider protocol from GEC Plessey in England, etc. In one embodiment, the invention is utilised in respect of a machinery stock. As an example of a machinery stock can be cited weaving machines which are installed in one or more weaving sheds and are respectively allocated one or more modules. In this case, the unit can comprise a service unit common to a number of weaving machines, preferably the majority or all of the total number of weaving machines. This service unit can comprise or contain a personal computer (PC).
In the case of weaving machines in a weaving shed, one or more modules assigned to a weaving machine are connected to a service function in the weaving shed. This service function can consist of beam-changing, bobbin-changing, etc. Service staff receive information in parallel with a service machine which is appropriately connected to the particular weaving machine. Function information can therefore appear both on the unit and in control apparatus belonging to the service machine, the function measure or instruction in question being able to be prepared simultaneously or in perfect coordination between the service machine and the staff involved. An effective synthesis is obtained for production and service measures which are necessary to the weaving machines in order to maintain effective production. The machines can be coupled together in a control network in which a particular machine has its own unique code and control system in order to prevent disturbances between the machines. The frequencies are preferably chosen within the broad-band range, i.e. 1 GHz or above, preferably the open ISM-band, but IR-frequencies and ultrasound frequencies can also be used. The latter particularly in respect of acoustic communication in an underwater environment.
The device according to the invention also relates to a system of mutually separate units which are intercommunicable by means of radiocommunications, these being able to be set up such that message channels can be realised between two or more of the said units. The radio communications operate here with an identification system in which a key allocation can be realised, which in a particular connection instance enables messages to be transferred between selected units only. The particular unit is further designed with a CAN-system (Controller Area Network), in which activations, control operations, functions, stimulations, readings, etc. in modules making up the unit are intercommunicable via a digital serial connection. The latter device is principally characterised by the fact that in each connection instance the key allocation between the units is based upon an identity/identities which, during a connection process for the connection in question, are acquired from a module in the CAN-system concerned and/or from a master system or master control centre. Further features of the devices in question can be derived from the following patent claims.
What primarily can be considered to be characteristic of a device according to the invention, comprising the module mentioned in the introduction, is that a radiocommunication apparatus is arranged for connection with a part belonging to a second module in the system for the establishment of a radiocommunication channel between the location for the placement of the first module and a location for the placement of the second module. At the location for the placement of the first module, radiocommunication equipment can be activated for initiation via a radio channel and the said part of the radiocommunication equipment by activation of a signal in the second module. This signal activation causes the first module to perform its particular control and/or supervisory function which then becomes able to be observed or registered in place of the first module.
In one embodiment, the CAN-system forms part of a machine-control system and/or process-control system in which a first signal exchange according to the CAN-protocol obtains between involved modules within the system for the control operation and the performance of the process. A first activation of the radiocommunication equipment at the first location hereupon gives rise to a second activation of circuits in the second module. This second activation induces the said signal activation in the second module.
In a further embodiment, the signal activation caused by the second activation gives rise to message initiation in the second module, which prepares to dispatch a message via the module""s communication circuit, over the connection to the first module. The second module is hereupon able to transmit the thus generated message, with a predetermined order of priority, in the ordinary message or signal exchange between the modules. In one embodiment, the second module can cause interruption to the ordinary message or signal exchange in the CAN-system. That signal activation in the second module which is herein. initiated by the second activation takes over the CAN-system for the generation and sending of one or more test messages via the communication circuit and the connection to the first module.
When its signal is activated on the basis of the second activation in the second module, the second module can imitate a control or supervisory function which can normally be found in the machine and/or process-control system. Alternatively, or as a supplement thereto, a control and/or supervisory function which is especially cut out for the testing function is generated.
The radiocommunication equipment preferably operates two-way (half or full duplex). This makes it possible for a stimulation of control or supervisory component(s) or equipment at the first module to produce a feedback to the second module, via the connection to the second module. The latter generates a stimulation-responding information signal, which is fed back to the radio equipment part situated at the first module. Information which is transferred via the radiocommunication equipment can thereby be indicated or presented on or at the said radiocommunication equipment part at the first module.
In one embodiment, the radiocommunication equipment part at the first module is connected to the control and or supervisory equipment served by the first module and/or directly to the module.
In one embodiment, the second module is arranged such that it is merely a so-called xe2x80x9cgatewayxe2x80x9d between the radiocommunication of the first unit and the CAN-system, i.e. a message from the first module via radio to the second module is converted there to a CAN-message and transmitted on the bus, and vice versa.
Further characteristics derive from the following patent claims and the description. The device also therefore works in cases where the equipment in the first module is stimulated, for example, manually, which stimulation can be monitored at the control or information-supplying unit to ascertain whether there are faults in the equipment and/or the communications.
Radiocommunication between control units and machines in machinery stocks can be economically established even where the machines operate with CAN-protocol. Repetition functions can be inserted into the CAN-system or the machine and/or process-control system, which means that connections can be established for even poorly accessible locations. Proven methods are in fact able to be used in connection with the radiocommunication control operation, as regards control desks, frequency usage, security arrangements, coding, keys, etc.
The above makes it possible for testing and function-checking to be easily carried out on CAN-modules, using simulated control operations and stimulations which are introduced to second modules at a distance from the first modules. The checks can be executed even if the connecting line is long, e.g. 800 m, or the modules are hidden from one another. The stimulations can also be carried out on the visually supervised module or its equipment/components and the reactions to such stimulations can be obtained in a second direction within the CAN-system and recorded at the location for the first module(s).